Ta có: \(\left(3-\dfrac{1}{4}+\dfrac{2}{3}\right)-\left(5+\dfrac{1}{3}-\dfrac{6}{5}\right)-\left(6-\dfrac{7}{4}-\dfrac{3}{2}\right)\\ =3-\dfrac{1}{4}+\dfrac{2}{3}-5-\dfrac{1}{3}+\dfrac{6}{5}-6+\dfrac{7}{4}+\dfrac{3}{2}\\ =\left(3-5-6\right)-\left(\dfrac{1}{4}-\dfrac{7}{4}\right)+\left(\dfrac{2}{3}-\dfrac{1}{3}\right)+\dfrac{6}{5}+\dfrac{3}{2}\\ =-8+\dfrac{3}{2}+\dfrac{1}{3}+\dfrac{6}{5}+\dfrac{3}{2}=-8+\left(\dfrac{3}{2}+\dfrac{3}{2}\right)+\left(\dfrac{1}{3}+\dfrac{6}{5}\right)\\ =-8+3+\dfrac{23}{15}\\ =-5+\dfrac{23}{15}\\ =-\dfrac{52}{15}\)
Cách khác:
\(\left(3-\dfrac{1}{4}+\dfrac{2}{3}\right)-\left(5+\dfrac{1}{3}-\dfrac{6}{5}\right)-\left(6-\dfrac{7}{4}-\dfrac{3}{2}\right)\\ =\dfrac{41}{12}-\dfrac{62}{15}-\dfrac{11}{4}\\ =-\dfrac{52}{15}\)
